1 /* SPDX-License-Identifier: GPL-2.0-only */ 2 /* 3 * Copyright (C) 2012 Regents of the University of California 4 * 5 * This file was copied from include/asm-generic/uaccess.h 6 */ 7 8 #ifndef _ASM_RISCV_UACCESS_H 9 #define _ASM_RISCV_UACCESS_H 10 11 /* 12 * User space memory access functions 13 */ 14 #include <linux/errno.h> 15 #include <linux/compiler.h> 16 #include <linux/thread_info.h> 17 #include <asm/byteorder.h> 18 #include <asm/extable.h> 19 #include <asm/asm.h> 20 21 #define __enable_user_access() \ 22 __asm__ __volatile__ ("csrs sstatus, %0" : : "r" (SR_SUM) : "memory") 23 #define __disable_user_access() \ 24 __asm__ __volatile__ ("csrc sstatus, %0" : : "r" (SR_SUM) : "memory") 25 26 /* 27 * The fs value determines whether argument validity checking should be 28 * performed or not. If get_fs() == USER_DS, checking is performed, with 29 * get_fs() == KERNEL_DS, checking is bypassed. 30 * 31 * For historical reasons, these macros are grossly misnamed. 32 */ 33 34 #define MAKE_MM_SEG(s) ((mm_segment_t) { (s) }) 35 36 #define KERNEL_DS MAKE_MM_SEG(~0UL) 37 #define USER_DS MAKE_MM_SEG(TASK_SIZE) 38 39 #define get_fs() (current_thread_info()->addr_limit) 40 41 static inline void set_fs(mm_segment_t fs) 42 { 43 current_thread_info()->addr_limit = fs; 44 } 45 46 #define segment_eq(a, b) ((a).seg == (b).seg) 47 48 #define user_addr_max() (get_fs().seg) 49 50 51 /** 52 * access_ok: - Checks if a user space pointer is valid 53 * @addr: User space pointer to start of block to check 54 * @size: Size of block to check 55 * 56 * Context: User context only. This function may sleep. 57 * 58 * Checks if a pointer to a block of memory in user space is valid. 59 * 60 * Returns true (nonzero) if the memory block may be valid, false (zero) 61 * if it is definitely invalid. 62 * 63 * Note that, depending on architecture, this function probably just 64 * checks that the pointer is in the user space range - after calling 65 * this function, memory access functions may still return -EFAULT. 66 */ 67 #define access_ok(addr, size) ({ \ 68 __chk_user_ptr(addr); \ 69 likely(__access_ok((unsigned long __force)(addr), (size))); \ 70 }) 71 72 /* 73 * Ensure that the range [addr, addr+size) is within the process's 74 * address space 75 */ 76 static inline int __access_ok(unsigned long addr, unsigned long size) 77 { 78 const mm_segment_t fs = get_fs(); 79 80 return size <= fs.seg && addr <= fs.seg - size; 81 } 82 83 /* 84 * The exception table consists of pairs of addresses: the first is the 85 * address of an instruction that is allowed to fault, and the second is 86 * the address at which the program should continue. No registers are 87 * modified, so it is entirely up to the continuation code to figure out 88 * what to do. 89 * 90 * All the routines below use bits of fixup code that are out of line 91 * with the main instruction path. This means when everything is well, 92 * we don't even have to jump over them. Further, they do not intrude 93 * on our cache or tlb entries. 94 */ 95 96 #define __LSW 0 97 #define __MSW 1 98 99 /* 100 * The "__xxx" versions of the user access functions do not verify the address 101 * space - it must have been done previously with a separate "access_ok()" 102 * call. 103 */ 104 105 #define __get_user_asm(insn, x, ptr, err) \ 106 do { \ 107 uintptr_t __tmp; \ 108 __typeof__(x) __x; \ 109 __enable_user_access(); \ 110 __asm__ __volatile__ ( \ 111 "1:\n" \ 112 " " insn " %1, %3\n" \ 113 "2:\n" \ 114 " .section .fixup,\"ax\"\n" \ 115 " .balign 4\n" \ 116 "3:\n" \ 117 " li %0, %4\n" \ 118 " li %1, 0\n" \ 119 " jump 2b, %2\n" \ 120 " .previous\n" \ 121 " .section __ex_table,\"a\"\n" \ 122 " .balign " RISCV_SZPTR "\n" \ 123 " " RISCV_PTR " 1b, 3b\n" \ 124 " .previous" \ 125 : "+r" (err), "=&r" (__x), "=r" (__tmp) \ 126 : "m" (*(ptr)), "i" (-EFAULT)); \ 127 __disable_user_access(); \ 128 (x) = __x; \ 129 } while (0) 130 131 #ifdef CONFIG_64BIT 132 #define __get_user_8(x, ptr, err) \ 133 __get_user_asm("ld", x, ptr, err) 134 #else /* !CONFIG_64BIT */ 135 #define __get_user_8(x, ptr, err) \ 136 do { \ 137 u32 __user *__ptr = (u32 __user *)(ptr); \ 138 u32 __lo, __hi; \ 139 uintptr_t __tmp; \ 140 __enable_user_access(); \ 141 __asm__ __volatile__ ( \ 142 "1:\n" \ 143 " lw %1, %4\n" \ 144 "2:\n" \ 145 " lw %2, %5\n" \ 146 "3:\n" \ 147 " .section .fixup,\"ax\"\n" \ 148 " .balign 4\n" \ 149 "4:\n" \ 150 " li %0, %6\n" \ 151 " li %1, 0\n" \ 152 " li %2, 0\n" \ 153 " jump 3b, %3\n" \ 154 " .previous\n" \ 155 " .section __ex_table,\"a\"\n" \ 156 " .balign " RISCV_SZPTR "\n" \ 157 " " RISCV_PTR " 1b, 4b\n" \ 158 " " RISCV_PTR " 2b, 4b\n" \ 159 " .previous" \ 160 : "+r" (err), "=&r" (__lo), "=r" (__hi), \ 161 "=r" (__tmp) \ 162 : "m" (__ptr[__LSW]), "m" (__ptr[__MSW]), \ 163 "i" (-EFAULT)); \ 164 __disable_user_access(); \ 165 (x) = (__typeof__(x))((__typeof__((x)-(x)))( \ 166 (((u64)__hi << 32) | __lo))); \ 167 } while (0) 168 #endif /* CONFIG_64BIT */ 169 170 171 /** 172 * __get_user: - Get a simple variable from user space, with less checking. 173 * @x: Variable to store result. 174 * @ptr: Source address, in user space. 175 * 176 * Context: User context only. This function may sleep. 177 * 178 * This macro copies a single simple variable from user space to kernel 179 * space. It supports simple types like char and int, but not larger 180 * data types like structures or arrays. 181 * 182 * @ptr must have pointer-to-simple-variable type, and the result of 183 * dereferencing @ptr must be assignable to @x without a cast. 184 * 185 * Caller must check the pointer with access_ok() before calling this 186 * function. 187 * 188 * Returns zero on success, or -EFAULT on error. 189 * On error, the variable @x is set to zero. 190 */ 191 #define __get_user(x, ptr) \ 192 ({ \ 193 register long __gu_err = 0; \ 194 const __typeof__(*(ptr)) __user *__gu_ptr = (ptr); \ 195 __chk_user_ptr(__gu_ptr); \ 196 switch (sizeof(*__gu_ptr)) { \ 197 case 1: \ 198 __get_user_asm("lb", (x), __gu_ptr, __gu_err); \ 199 break; \ 200 case 2: \ 201 __get_user_asm("lh", (x), __gu_ptr, __gu_err); \ 202 break; \ 203 case 4: \ 204 __get_user_asm("lw", (x), __gu_ptr, __gu_err); \ 205 break; \ 206 case 8: \ 207 __get_user_8((x), __gu_ptr, __gu_err); \ 208 break; \ 209 default: \ 210 BUILD_BUG(); \ 211 } \ 212 __gu_err; \ 213 }) 214 215 /** 216 * get_user: - Get a simple variable from user space. 217 * @x: Variable to store result. 218 * @ptr: Source address, in user space. 219 * 220 * Context: User context only. This function may sleep. 221 * 222 * This macro copies a single simple variable from user space to kernel 223 * space. It supports simple types like char and int, but not larger 224 * data types like structures or arrays. 225 * 226 * @ptr must have pointer-to-simple-variable type, and the result of 227 * dereferencing @ptr must be assignable to @x without a cast. 228 * 229 * Returns zero on success, or -EFAULT on error. 230 * On error, the variable @x is set to zero. 231 */ 232 #define get_user(x, ptr) \ 233 ({ \ 234 const __typeof__(*(ptr)) __user *__p = (ptr); \ 235 might_fault(); \ 236 access_ok(__p, sizeof(*__p)) ? \ 237 __get_user((x), __p) : \ 238 ((x) = 0, -EFAULT); \ 239 }) 240 241 #define __put_user_asm(insn, x, ptr, err) \ 242 do { \ 243 uintptr_t __tmp; \ 244 __typeof__(*(ptr)) __x = x; \ 245 __enable_user_access(); \ 246 __asm__ __volatile__ ( \ 247 "1:\n" \ 248 " " insn " %z3, %2\n" \ 249 "2:\n" \ 250 " .section .fixup,\"ax\"\n" \ 251 " .balign 4\n" \ 252 "3:\n" \ 253 " li %0, %4\n" \ 254 " jump 2b, %1\n" \ 255 " .previous\n" \ 256 " .section __ex_table,\"a\"\n" \ 257 " .balign " RISCV_SZPTR "\n" \ 258 " " RISCV_PTR " 1b, 3b\n" \ 259 " .previous" \ 260 : "+r" (err), "=r" (__tmp), "=m" (*(ptr)) \ 261 : "rJ" (__x), "i" (-EFAULT)); \ 262 __disable_user_access(); \ 263 } while (0) 264 265 #ifdef CONFIG_64BIT 266 #define __put_user_8(x, ptr, err) \ 267 __put_user_asm("sd", x, ptr, err) 268 #else /* !CONFIG_64BIT */ 269 #define __put_user_8(x, ptr, err) \ 270 do { \ 271 u32 __user *__ptr = (u32 __user *)(ptr); \ 272 u64 __x = (__typeof__((x)-(x)))(x); \ 273 uintptr_t __tmp; \ 274 __enable_user_access(); \ 275 __asm__ __volatile__ ( \ 276 "1:\n" \ 277 " sw %z4, %2\n" \ 278 "2:\n" \ 279 " sw %z5, %3\n" \ 280 "3:\n" \ 281 " .section .fixup,\"ax\"\n" \ 282 " .balign 4\n" \ 283 "4:\n" \ 284 " li %0, %6\n" \ 285 " jump 3b, %1\n" \ 286 " .previous\n" \ 287 " .section __ex_table,\"a\"\n" \ 288 " .balign " RISCV_SZPTR "\n" \ 289 " " RISCV_PTR " 1b, 4b\n" \ 290 " " RISCV_PTR " 2b, 4b\n" \ 291 " .previous" \ 292 : "+r" (err), "=r" (__tmp), \ 293 "=m" (__ptr[__LSW]), \ 294 "=m" (__ptr[__MSW]) \ 295 : "rJ" (__x), "rJ" (__x >> 32), "i" (-EFAULT)); \ 296 __disable_user_access(); \ 297 } while (0) 298 #endif /* CONFIG_64BIT */ 299 300 301 /** 302 * __put_user: - Write a simple value into user space, with less checking. 303 * @x: Value to copy to user space. 304 * @ptr: Destination address, in user space. 305 * 306 * Context: User context only. This function may sleep. 307 * 308 * This macro copies a single simple value from kernel space to user 309 * space. It supports simple types like char and int, but not larger 310 * data types like structures or arrays. 311 * 312 * @ptr must have pointer-to-simple-variable type, and @x must be assignable 313 * to the result of dereferencing @ptr. 314 * 315 * Caller must check the pointer with access_ok() before calling this 316 * function. 317 * 318 * Returns zero on success, or -EFAULT on error. 319 */ 320 #define __put_user(x, ptr) \ 321 ({ \ 322 register long __pu_err = 0; \ 323 __typeof__(*(ptr)) __user *__gu_ptr = (ptr); \ 324 __chk_user_ptr(__gu_ptr); \ 325 switch (sizeof(*__gu_ptr)) { \ 326 case 1: \ 327 __put_user_asm("sb", (x), __gu_ptr, __pu_err); \ 328 break; \ 329 case 2: \ 330 __put_user_asm("sh", (x), __gu_ptr, __pu_err); \ 331 break; \ 332 case 4: \ 333 __put_user_asm("sw", (x), __gu_ptr, __pu_err); \ 334 break; \ 335 case 8: \ 336 __put_user_8((x), __gu_ptr, __pu_err); \ 337 break; \ 338 default: \ 339 BUILD_BUG(); \ 340 } \ 341 __pu_err; \ 342 }) 343 344 /** 345 * put_user: - Write a simple value into user space. 346 * @x: Value to copy to user space. 347 * @ptr: Destination address, in user space. 348 * 349 * Context: User context only. This function may sleep. 350 * 351 * This macro copies a single simple value from kernel space to user 352 * space. It supports simple types like char and int, but not larger 353 * data types like structures or arrays. 354 * 355 * @ptr must have pointer-to-simple-variable type, and @x must be assignable 356 * to the result of dereferencing @ptr. 357 * 358 * Returns zero on success, or -EFAULT on error. 359 */ 360 #define put_user(x, ptr) \ 361 ({ \ 362 __typeof__(*(ptr)) __user *__p = (ptr); \ 363 might_fault(); \ 364 access_ok(__p, sizeof(*__p)) ? \ 365 __put_user((x), __p) : \ 366 -EFAULT; \ 367 }) 368 369 370 extern unsigned long __must_check __asm_copy_to_user(void __user *to, 371 const void *from, unsigned long n); 372 extern unsigned long __must_check __asm_copy_from_user(void *to, 373 const void __user *from, unsigned long n); 374 375 static inline unsigned long 376 raw_copy_from_user(void *to, const void __user *from, unsigned long n) 377 { 378 return __asm_copy_from_user(to, from, n); 379 } 380 381 static inline unsigned long 382 raw_copy_to_user(void __user *to, const void *from, unsigned long n) 383 { 384 return __asm_copy_to_user(to, from, n); 385 } 386 387 extern long strncpy_from_user(char *dest, const char __user *src, long count); 388 389 extern long __must_check strlen_user(const char __user *str); 390 extern long __must_check strnlen_user(const char __user *str, long n); 391 392 extern 393 unsigned long __must_check __clear_user(void __user *addr, unsigned long n); 394 395 static inline 396 unsigned long __must_check clear_user(void __user *to, unsigned long n) 397 { 398 might_fault(); 399 return access_ok(to, n) ? 400 __clear_user(to, n) : n; 401 } 402 403 /* 404 * Atomic compare-and-exchange, but with a fixup for userspace faults. Faults 405 * will set "err" to -EFAULT, while successful accesses return the previous 406 * value. 407 */ 408 #define __cmpxchg_user(ptr, old, new, err, size, lrb, scb) \ 409 ({ \ 410 __typeof__(ptr) __ptr = (ptr); \ 411 __typeof__(*(ptr)) __old = (old); \ 412 __typeof__(*(ptr)) __new = (new); \ 413 __typeof__(*(ptr)) __ret; \ 414 __typeof__(err) __err = 0; \ 415 register unsigned int __rc; \ 416 __enable_user_access(); \ 417 switch (size) { \ 418 case 4: \ 419 __asm__ __volatile__ ( \ 420 "0:\n" \ 421 " lr.w" #scb " %[ret], %[ptr]\n" \ 422 " bne %[ret], %z[old], 1f\n" \ 423 " sc.w" #lrb " %[rc], %z[new], %[ptr]\n" \ 424 " bnez %[rc], 0b\n" \ 425 "1:\n" \ 426 ".section .fixup,\"ax\"\n" \ 427 ".balign 4\n" \ 428 "2:\n" \ 429 " li %[err], %[efault]\n" \ 430 " jump 1b, %[rc]\n" \ 431 ".previous\n" \ 432 ".section __ex_table,\"a\"\n" \ 433 ".balign " RISCV_SZPTR "\n" \ 434 " " RISCV_PTR " 1b, 2b\n" \ 435 ".previous\n" \ 436 : [ret] "=&r" (__ret), \ 437 [rc] "=&r" (__rc), \ 438 [ptr] "+A" (*__ptr), \ 439 [err] "=&r" (__err) \ 440 : [old] "rJ" (__old), \ 441 [new] "rJ" (__new), \ 442 [efault] "i" (-EFAULT)); \ 443 break; \ 444 case 8: \ 445 __asm__ __volatile__ ( \ 446 "0:\n" \ 447 " lr.d" #scb " %[ret], %[ptr]\n" \ 448 " bne %[ret], %z[old], 1f\n" \ 449 " sc.d" #lrb " %[rc], %z[new], %[ptr]\n" \ 450 " bnez %[rc], 0b\n" \ 451 "1:\n" \ 452 ".section .fixup,\"ax\"\n" \ 453 ".balign 4\n" \ 454 "2:\n" \ 455 " li %[err], %[efault]\n" \ 456 " jump 1b, %[rc]\n" \ 457 ".previous\n" \ 458 ".section __ex_table,\"a\"\n" \ 459 ".balign " RISCV_SZPTR "\n" \ 460 " " RISCV_PTR " 1b, 2b\n" \ 461 ".previous\n" \ 462 : [ret] "=&r" (__ret), \ 463 [rc] "=&r" (__rc), \ 464 [ptr] "+A" (*__ptr), \ 465 [err] "=&r" (__err) \ 466 : [old] "rJ" (__old), \ 467 [new] "rJ" (__new), \ 468 [efault] "i" (-EFAULT)); \ 469 break; \ 470 default: \ 471 BUILD_BUG(); \ 472 } \ 473 __disable_user_access(); \ 474 (err) = __err; \ 475 __ret; \ 476 }) 477 478 #endif /* _ASM_RISCV_UACCESS_H */ 479